(cba:news) MASTER OT J040552.59+274716.7, and others

Joe Patterson jop at astro.columbia.edu
Tue Sep 10 01:15:10 EDT 2013


Dear CBAers,

I'm a little communications-hampered here in Sicily for a CV 
conference... but this (details below, but also see ATEL 5369) 
definitely looks like it's up our alley.  Decently well-positioned, 
easily good enough for deciphering aliases with a longitude spread among 
our observatories.  Fire away with the usual approach - time series 
photometry in unfiltered light, preferably with time resolution of 50-80 
s or better.

Re other stars.  V1101 Aql continues to delight, but is now coming off 
another max, and I'd suggest continuing coverage for just one more week, 
then quitting.  I think the filtered-photometry approach can be ended 
now.  At first glance, the data suggest the usual result for CVs: the 
periodic signals are white (and thus no significant advantage in using 
filters - except for very bright targets of course).

NR TrA can also be ended now.  It was an experiment in defying the 
onrushing evening twilight.  Those experiments always lose in the end... 
and besides, we got great results.  Berto, Josch, Bob Rea, and Gordon 
Myers manned the ramparts.  It amazes me how these "young old novae" 
have such similar orbital light curves - while all the old guys (novae 
 >50 years ago) revert to their own characteristic and highly varied 
light-curve shapes.

BW Scl is definitely worth continuing.  It shows strong "high-epsilon" 
or "2:1" superhumps - signals exceeding Porb not by ~2%, but more like 
7-8%.  This phenomenon still doesn't have a name, and most CV 
astronomers have never heard of it.  It's time for us to write a really 
good paper about them, and I think BW Scl is the ideal excuse for it, 
because the waves are quite strong, with maxima visible in the light 
curve (therefore easily timed).  Berto, Josch, and Bob Rea have been 
steadily observing.  With some coverage from Greg Bolt (Perth) and 
Arto(Chile, but with high density of points), we could track this all 
the way around the globe.  The reason that's highly desirable - rather 
than just a point of pride - is that the waves are *much less stable in 
phase* than their better-known 3:1 cousins, regular old superhmps.  So 
we gotta track them more closely, at least some of the time.

Enrique has begun the year's coverage on PX And, and it's also time (or 
almost time?) to begin on LT Eri and AH Men.  Each of these stars shows 
positive superhumps, negative superhumps, and "nodal precession" (or 
anyway, a long-period signal at the beat frequency of orbit and negative 
superhump.  Or at least they did at some point in our scattered coverage 
in past years.  It's time (or maybe almost time - it depends on whether 
you like morning observing!) for an *intensive* campaign which will nail 
these results down.

Finally, I plead again for coverage of V1494 Aql.  Remember that 
brilliant star in November 1999?  Let's give it some love now! 
Enrique's data confirm the (somewhat shallow) eclipses, and I think also 
the double-humped light curve that may yield the temperature of the 
still-hot-and-glowing white dwarf.  Can't tell yet re superhumps.  It's 
about 17.2, a pretty hard target - but can be done in good conditions by 
many of you.

Oops, also finally... ASAS-SN13ck is turning out great!  Keep the 
campaign going on that star.  BTW my email access is very poor here, and 
I hope you guys with actual telescopes and live computers will use 
cba-chat and cba-news to communicate useful stuff in the next 7-10 days, 
esp. as regards these new or lesser-known targets.

joe


-------- Original Message --------
							     ATEL #5381

Title:	Spectroscopy of MASTER OT J040552.59+274716.7 in Taurus
Author:	R. M. Wagner (Ohio State), C. E. Woodward (Minnesota), and
		S. G. Starrfield (Arizona State)
Queries:	mwagner at lbto.org
Posted:	9 Sep 2013; 16:53 UT
Subjects:Optical, Cataclysmic Variable, Nova, Transient

We observed the optical transient designated MASTER OT J040552.59+274716.7
reported by Denisenko et al. (ATEL #5369) on 2013-09-06.4090 UT with the
2.4 m Hiltner telescope on Kitt Peak, Arizona.  We confirm the presence
of a bright transient at the position reported by Denisenko et al. 
Furthermore,
we obtained several spectra of the transient using the OSU CCD Spectrograph
(CCDS; range: 366-730 nm; resolution: 0.9 nm).  The average spectrum 
exhibits
emission lines of the Balmer series of hydrogen; He I 706.5, 667.8, 587.5
nm; He II 468.6 nm; and perhaps N III 464.0 nm.  The equivalent width of
H-alpha emission was 1.60 nm and with a FWHM of 1.32 nm (corrected for
instrumental resolution).  In addition, weaker H-beta and several of the
higher order Balmer emission lines are superposed on broad (full-width
of 6.2 nm at H-beta) absorption troughs.  The spectrum is characteristic
of a dwarf nova near maximum light.  The appearance of the spectrum and
outburst amplitude of at least 7.5 mag reported by Denisenko et al. suggests
that the transient is a member of the WZ Sge subclass.  Further 
time-resolved
photometric observations are encouraged.



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